- Mechanistic Insights into Enantioselective C-H Photooxygenation of Aldehydes via Enamine Catalysis
-
Organocatalytic photooxygenation of aldehydes at the α-position proceeds via enamine catalysis, though enamines should be easily oxidized by singlet oxygen respectively to amides and carbonyl compounds. Moreover, the formation of a zwitterionic enamine peroxide intermediate was postulated based on experimental and theoretical data. The reaction affords desired diols (after in situ reduction) in a decent yield and (S)- or (R)-enantioselectivity depending on a catalyst used. The (S)-enantiomer predominated in imidazolidinone-catalyzed reactions, while prolineamides assured the formation of the (R)-stereoisomer. DFT calculation suggests that the enamine-oxygen complex with the lowest energy has the E,s-cis conformation for the prolineamide derivative and E,s-trans for the imidazolidinone catalyst, explaining the opposite stereoselectivity in the photooxygenation reaction.
- Walaszek, Dominika J.,Rybicka-Jasińska, Katarzyna,Smoleń, Sabina,Karczewski, Maksymilian,Gryko, Dorota
-
p. 2061 - 2070
(2015/06/23)
-
- New applications of PhI(OAc)2 in synthesis: Total synthesis and SAR development of potent antitumor natural product psymberin/irciniastatin A
-
A novel PhI(OAc)2-mediated oxidative cyclization reaction is discovered for the synthesis of a-oxy N-acyl aminals and hemiaminals in good yields from readily synthesized N-acyl enamines. This methodology represents a cascade process to construct the core structure of the pederin family of natural products. The total synthesis of psymberin, a member of the pederin family, is accomplished using this ring-closure reaction as the key step. This new method is further showcased in the preparation of advanced psymberin analogues. The biological data of these analogues are presented. Georg Thieme Verlag Stuttgart.
- Shao, Ning,Huang, Xianhai,Palani, Anandan,Aslanian, Robert,Buevich, Alexei,Piwinski, John,Huryk, Robert,Seidel-Dugan, Cynthia
-
scheme or table
p. 2855 - 2872
(2010/03/05)
-